Bladder stones, also called bladder calculi or uroliths, are solid pieces of minerals and protein that form in the urinary bladder. The urinary bladder is an organ located in the front of the pelvis that collects and stores urine. Bladder stones may be hard or soft, and jagged or smooth, depending on their composition.
Bladder stones begin as tiny crystalline formations of struvite and calcium oxalate and can grow to more than an inch in diameter. The stones can interfere with the flow of urine and can cause pain during urination. Bladder stones also can scrape or even pierce the wall of the bladder, causing the bladder to bleed or become infected. However, stones that form in the bladder are much less common than kidney stones .
Bladder stones affect 5-10% of the populations of developed countries. The majority of all bladder stones occur in men over age 50, most of whom have enlarged prostate glands or urinary tract infections (UTIs). Bladder stones rarely occur in children or African Americans. The incidence of bladder stones in the United States declined during the twentieth century in response to improved nutrition , including adequate fluid intake and timely detection and treatment of urinary tract infections. In the twenty-first century, bladder stones are most prevalent in Middle and Far Eastern countries, North Africa and some other African countries.
Causes and symptoms
The precise reasons that bladder stones form is not fully understood. They frequently arise in response to UTIs, blockage in the urinary tract, or in men who have enlarged prostate glands. Persons with a neurogenic bladder in which nerves to the bladder are damaged; those with outpouchings called diverticula, of weakened bladder walls; and people who use urinary catheters are at increased risk of developing bladder stones. Diet and the volume of fluid consumed also appear to influence the risk of stone formation. People with gout , a condition in which abnormally high levels of uric acid in the blood produce uric acid deposits in joints, are at risk of developing bladder stones composed of uric acid.
Bladder stones may slowly form without any signs or symptoms. The stones may scratch the bladder wall or block the flow of urine and provoke symptoms including:
- dark colored urine or blood in the urine
- difficultly urinating or maintaining urine flow
- frequent, urgent need to urinate, especially during the night
- lower abdominal pain or pressure
- urine leakage or incontinence
- pain or discomfort in the penis
The diagnosis of bladder stones begins with a physical examination, during which the lower abdomen, back, and genital area may be palpated (examined by touch) to determine consistency, size, texture and tenderness. Physical examination of men may include a rectal examination to find out if the prostate gland is enlarged. Urinalysis, the collection of a sample of urine for examination under the microscope, can detect whether there are blood, crystallized minerals, or indications of infection in the urine.
Cytoscopy, examination of the bladder and urethra using a cystoscope, a long, thin tube with a light that is inserted into the urethra, helps to determine the location, number and size of the stones in the bladder. Imaging studies, such as x ray, computed tomography (CT) and ultrasound can help to determine whether there are stones in the bladder. An intravenous pyelogram (IVP), an x-ray study of the kidneys, ureters and bladder taken after injection of a dye into a blood vessel, enables identification of stones and their locations in the bladder and the rest of the urinary tract.
When bladder stones are small, many people are able to pass bladder stones on their own by drinking an additional six to eight glasses of water per day to increase urine flow.
QUESTIONS TO ASK YOUR DOCTOR
- Which tests will best determine the size, number and location of the bladder stones?
- Are the stones small enough that I can pass them on my own in the urine?
- If ample fluid consumption fails to flush out the stones, what are the treatment options?
- What is the probable cause of the bladder stones?
- What actions can be taken to prevent recurrences?
If a bladder stone does not pass on its own, is large, or is causing other problems, then the doctor generally recommends removing the stone. A bladder stone may be removed in a procedure called cystolitholapaxy. During cystolitholapaxy, a cytoscope with a small camera is inserted into the bladder through the urethra (the tube through which urine leaves the body) to enable visualization of the stone. Once the stone is located, it can be broken into small bits using a mechanical device, laser, or ultrasound, and then flushed out of the bladder. Cystolitholapaxy is generally performed under local or general anesthesia to minimize pain or discomfort during the procedure. Antibiotics may be prescribed before the procedure to reduce the risk of infection.
Bladder stones that are too large to remove using cystolitholapaxy may be removed surgically through an incision in the bladder. If the bladder stone is related to another urological problem such as an enlarged prostate gland or a blockage at the base of the bladder that obstructs the flow of urine into the urethra, then these underlying problems also may be addressed during surgery.
Ensuring adequate hydration by drinking plenty of water and other fluids may help to prevent the formation of bladder stones and to prevent recurrences. Since consumption of cranberry and lingonberry juice may help to prevent UTIs, which may promote bladder stone formation, many people who develop recurrent UTIs incorporate these into their diets. Fresh, unsweetened lemon juice also helps to flush out the urinary tract.
Cystolitholapaxy —Removal of bladder stones by breaking them in the bladder and then irrigating the bladder to flush out the fragments.
Cytoscopy —Examination of the bladder and urethra using a cystoscope, a long, thin tube with a light and lens that is inserted into the urethra. A cytoscope may have a tool to remove tissue for examination under a microscope.
Prostate —In males, the gland surrounding the neck of the bladder and urethra that controls the release of urine from the bladder and secretes a fluid component of semen.
Recurrence —The return of a sign, symptom or disease after a successful treatment and remission.
Uroliths —Urinary stones or calculi, crystals of concentrated minerals.
The outlook for persons with bladder stones is usually excellent. Most bladder stones are readily passed in the urine and pose no real threat to the health or integrity of the bladder and the rest of the urinary tract. It is important to identify and effectively address the cause of bladder stones to prevent recurrences. Without resolution of the underlying cause about half of all persons with bladder stones experience a recurrence within five years.
Bladder stones that are left untreated and remain in the bladder can cause painful urination, chronic UTIs and may damage the walls of the bladder or indirectly injure the kidneys. Because they may scratch and rub away the bladder wall, bladder stones can promote the irritation and inflammation that can increase the risk of developing bladder cancer .
Consuming ample amounts of water and other fluids may help to prevent the formation of bladder stones by diluting the concentration of minerals present in the bladder and by helping to prevent UTIs. Daily consumption of cranberry juice also may help to prevent UTIs and stone formation. Timely detection and treatment of urological problems such as a UTI, enlarged prostate or obstruction of the urethra may prevent development and recurrence of stones.
Bartoletti, R., et al. “Epidemiology and Risk Factors in Urolithiasis.” Urologia Internationalis 79, suppl. 1 (2007).
Vandenbroucke, Jan P. “Commentary: Treatment of Bladder Stones and Probabilistic Reasoning in Medicine: An 1835 Account and its Lessons for the Present.” International Journal of Epidemiology 30, no. 6 (2001).
Basler, Joseph. “Bladder Stones.” eMedicine.com. August 10, 2007 [cited April 5, 2008]. WebMD. http://www.emedicine.com/med/topic2852.htm.
Sherman, Neil D. “Bladder Stones.” MedlinePlus. June 16, 2006 [cited April 5, 2008]. National Institutes of Health. http://www.nlm.nih.gov/medlineplus/ency/article/001275.htm.
American Foundation for Urologic Disease, 1000 Corporate Blvd., Linthicum, Maryland, 21090, (410) 689-3700, (866) RING-AUA, (410) 689-3800, http://www.auafoundation.org.
Barbara Wexler MPH